GM Service Manual Online
For 1990-2009 cars only

Scan Tool Output Control

Additional Menu Selection(s)

Description

AIR Solenoid

Engine Output Controls / AIR System

Enables the secondary air injection (AIR) solenoid valve and the AIR pump relay simultaneously. The normal commanded state is NONE. When commanded ON, the AIR solenoid supplies vacuum pressure in order to open the AIR shut-off valve. The AIR pump relay is also energized in order to turn ON the AIR pump

The solenoid and the pump remain in the commanded state for only 5 seconds. A second or subsequent request for commanded state ON is rejected until 30 seconds have passed, or the ignition switch is cycled.

A/C Compressor

Engine Output Controls

Activates the A/C compressor clutch relay and cooling fan 1 relay. The normal commanded state of both relays is NONE. The A/C compressor relay status can be monitored on the scan tool data parameter A/C Relay Command. The PCM allows relay control when the following conditions are met:

    • The ignition is ON or the engine is running
    • The blower motor select switch is ON
    • The powertrain control module (PCM) will inhibit the operation of the A/C relay when the ambient air temperature low enough to cause icing of the evaporator core.

Auxiliary Intake Air Control Solenoid

Engine Output Controls

Activates the auxiliary intake air control solenoid switching solenoid. The normal commanded state is NONE. When commanded ON, the solenoid supplies vacuum pressure in order to close the auxiliary air inlet door.

The solenoid remains in the commanded state until cancelled by the scan tool or until vehicle speed is detected.

Cam Valve Timing

Engine Output Controls

Activates the camshaft position (CMP) actuator solenoid valve. The normal commanded state of the CMP actuator solenoid is NONE. When commanded ON, the CMP actuator solenoid is operated at 100 percent duty cycle and the engine will stall. The PCM allows CMP actuator solenoid control when the following conditions are met:

    • DTC P1010, P1011, or P1012 are not set.
    • The engine is running
    • No vehicle speed is detected

Operation of the CMP actuator solenoid can be monitored on the parameter Camshaft Phase Solenoid Command. The solenoid remains in the commanded state until any of the following conditions occur:

    • Cancelled by the scan tool
    • The engine stalls
    • Vehicle speed is detected

Check Mode

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Check Mode engine operation enhances the PCM's ability to detect certain engine control system malfunctions. When entering the output control, the default commanded state is NONE or NORMAL. In order to enter check mode operation refer to Service Bay Test .

Check mode operation can be monitored on the data parameter Diagnostic Mode. The PCM remains in the commanded state until cancelled by the scan tool or until the ignition switch is cycled.

EVAP Purge Solenoid

Engine Output Controls / EVAP System

Activates the EVAP canister purge valve. The normal commanded state is NONE. When commanded ON, the purge solenoid operates near 50 percent duty cycle. The solenoid remains in the commanded state for a maximum of 5 seconds, or until vehicle speed is detected.

EVAP Vacuum Leak Pump

Engine Output Controls / EVAP System

Activates the EVAP vacuum leak pump located in the EVAP vacuum leak pump assembly. The normal commanded state is NONE. When commanded ON, the vacuum pump generates vacuum pressure. The pump remains in the commanded state for a maximum of 5 seconds, or until engine speed is detected or system pressure exceeds -39.8 mm Hg (-21.3 in H2O).

EVAP Vent Solenoid

Engine Output Controls / EVAP System

Activates the EVAP vent solenoid located in the EVAP vacuum leak pump assembly. The normal commanded state is NONE. When commanded ON, the vent valve switches to non-venting. The solenoid remains in the commanded state for a maximum of 5 seconds, or until vehicle speed is detected.

EVAP Service Bay Test

Engine Output Controls / EVAP System

Activates the EVAP purge solenoid, the EVAP vent solenoid, and the EVAP vacuum leak pump. Both EVAP solenoids and the vacuum leak pump are automatically sequenced on and off while vapor pressure in the EVAP system is monitored by the fuel tank pressure (FTP) sensor. The service bay test can take 2-8 minutes in order to run. The PCM allows the service bay test to run when the following conditions are met:

    • No diagnostic trouble codes (DTC) are set.
    • The ignition is ON, with the engine OFF.
    • No vehicle speed is detected
    • System pressure is less than -39.8 mm Hg (-21.3 in H2O)

If after clearing codes or running a second test the scan tool displays Test Failed, the request for the service bay test has been rejected. Exit the test screen on the scan tool and turn OFF the ignition for 30 seconds, before attempting the service bay test again. For complete information about the service bay test refer to Service Bay Test .

Fuel Injector Modification

Fuel System

Enables fuel injector to INCREASE or DECREASE fuel delivery by changing fuel injector pulse width (PW). The PCM increases or decreases the PW in 1 percent increments as commanded. The commanded range is from -12 to +25 percent.

The solenoid remains in the commanded state until cancelled by the scan tool or until engine speed exceeds 3,000 RPM.

Fuel Pump

Engine Output Controls

Controls the fuel pump relay. The normal commanded state is NONE. When commanded ON, the PCM turns the fuel pump relay ON. If the engine is running, fuel pump command is disabled. The relay remains in the commanded state until cancelled by the scan tool or until engine speed is detected.

Misfire Graphic

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Displays the accumulated misfires occurring in each cylinder in a bar graph. The scan tool allows for a reset of the misfire graph.

RPM Control

IAC System

Activates the idle air control (IAC) valve in order to change engine RPM. The normal commanded state is 27-34 percent duty cycle. IAC valve operation can be monitored on the scan tool data parameter IAC Motor Command. In order to enable RPM control, the vehicle must be in Park or Neutral, and all instructions on the scan tool must be completed. The system will INCREASE or DECREASE the RPM within the IAC Motor Command range of 35-90 percent. The engine speed will increase or decrease accordingly from 750-3,000 RPM at approximately 80°C (176°F).

The system remains in the commanded state until cancelled by the scan tool or when vehicle speed is detected.

Rocker Arm Oil Control Solenoid

Engine Output Controls

Activates the rocker arm oil control solenoid valve. The normal commanded state of the rocker arm oil control solenoid is NONE. When commanded ON, the rocker arm oil control solenoid is operated at 100 percent duty cycle and the engine will stall. The PCM allows solenoid control when the following conditions are met:

    • DTC P2645, P2646, or P2647 are not set.
    • The engine is running and engine speed is less than 2,500 RPM.
    • The engine coolant temperature is more than 65°C (149°F).
    • No vehicle speed is detected

The solenoid remains in the commanded state until any of the following conditions occur:

    • Cancelled by the scan tool
    • The engine stalls
    • Engine speed exceeds 2,500 RPM
    • Vehicle speed is detected